U.S. patent number 6,994,290 [Application Number 10/437,384] was granted by the patent office on 2006-02-07 for magnetic tape manufacturing apparatus.
This patent grant is currently assigned to Fuji Photo Film Co., Ltd.. Invention is credited to Hiromichi Ito.
United States Patent |
6,994,290 |
Ito |
February 7, 2006 |
Magnetic tape manufacturing apparatus
Abstract
The magnetic tape manufacturing apparatus draws out a wide
web-like magnetic tape material wound in roll form from the
delivery side, slits the magnetic tape material into a plurality of
narrow magnetic tapes by use of a slitter while transporting the
magnetic tape material, and winds the narrow magnetic tapes on
cores on the winding side through a tape transporting device. In
the tape transporting device, roller members supporting the narrow
magnetic tapes are mounted on supporting shafts, respectively, and
an eddy current type clutch is internally mounted on at least one
of the supporting shafts so that the eddy current type clutch
controls rotation of the one of supporting shafts to control
tension of the narrow magnetic tape supported on the roller member
mounted on the one of supporting shafts. Hence, by making the
tension of the individual magnetic tapes uniform, productivity and
product quality can be stabilized and improved and yield can also
be improved.
Inventors: |
Ito; Hiromichi (Odawara,
JP) |
Assignee: |
Fuji Photo Film Co., Ltd.
(Kanagawa, JP)
|
Family
ID: |
29416963 |
Appl.
No.: |
10/437,384 |
Filed: |
May 14, 2003 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20030213430 A1 |
Nov 20, 2003 |
|
Foreign Application Priority Data
|
|
|
|
|
May 16, 2002 [JP] |
|
|
2002-140910 |
|
Current U.S.
Class: |
242/530;
242/419.9; G9B/15.048 |
Current CPC
Class: |
B65H
18/103 (20130101); B65H 23/26 (20130101); B65H
35/02 (20130101); G11B 15/43 (20130101); B65H
2220/09 (20130101); B65H 2403/7241 (20130101); B65H
2701/378 (20130101); B65H 2301/4148 (20130101) |
Current International
Class: |
B65H
18/08 (20060101) |
Field of
Search: |
;242/530.1,530.3,419.9,615.4,530,615.2,156.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2001-187660 |
|
Jul 2001 |
|
JP |
|
WO 90/05690 |
|
May 1990 |
|
WO |
|
Primary Examiner: Nguyen; John Q.
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. A magnetic tape manufacturing apparatus, comprising: a tape
supply device which draws out a wide web-like magnetic tape
material wound in roll form from a delivery side; a slitter which
slits the magnetic tape material into a plurality of narrow
magnetic tapes; a tape take-up device which takes up the narrow
magnetic tapes individually on cores on a take-up side; and a tape
transporting device which is provided between the slitter and the
tape take-up device and guides the narrow magnetic tapes to the
tape take-up device, wherein: the tape transporting device includes
a plurality of roller members which support the narrow magnetic
tapes, respectively, the plurality of roller members are mounted on
a plurality of supporting shafts, respectively, at least one eddy
current clutch is mounted on at least one of the plurality of
supporting shafts, said at least one eddy current clutch being
internally mounted in a corresponding one of said plurality of
roller members, said at least one eddy current type clutch
controlling rotation of the corresponding one of said roller
members mounted on said one of the plurality of supporting shafts
to control tension of the narrow magnetic tape supported on the
corresponding one of said roller members, at least one tension
detection device provided for at least one of the plurality of
narrow magnetic tapes, and a means for providing feedback control
of a number of revolutions of the at least one supporting shaft
based on a tension detected by the tension detection device to
control rotation of the at least one of the supporting shafts to
control the tension of the magnetic tape supported by the one of
said plurality of roller members.
2. The magnetic tape manufacturing apparatus according to claim 1,
wherein a torsion force is applied to the corresponding one of said
roller members proportional to a difference in rotational speed
between the corresponding one of said roller members and said one
of the plurality of supporting shafts through said at least one
eddy current clutch.
3. The magnetic tape manufacturing apparatus according to claim 1,
wherein at least one groove for excluding entrained air of at least
one narrow magnetic tape is formed in an outer peripheral surface
of at least one of the roller members.
4. A magnetic tape manufacturing apparatus, comprising: a tape
supply device which draws out a wide web-like magnetic tape
material wound in roll form from a delivery side; a slitter which
slits the magnetic tape material into a plurality of narrow
magnetic tapes; a tape take-up device which takes up the narrow
magnetic tapes individually on cores on a take-up side; and a tape
transporting device which is provided between the slitter and the
tape take-up device and guides the narrow magnetic tapes to the
tape take-up device, wherein: the tape transporting device includes
a plurality of roller members which support the narrow magnetic
tapes, respectivel, the plurality of roller members are mounted on
a plurality of supporting shafts, respectively, at least one eddy
current clutch is mounted on at least one of the plurality of
supporting shafts, said at least one eddy current clutch being
internally mounted in a corresponding one of said plurality of
roller members, said at least one eddy current type clutch
controlling rotation of the corresponding one of said roller
members mounted on said one of the plurality of supporting shafts
to control tension of the narrow magnetic tape supported on the
corresponding one of said roller members, a plurality of tension
detection devices, wherein one tension detection device is provided
for each one of the plurality of narrow magnetic tapes, and a means
for providing feedback control of a number of revolutions of the at
least one supporting shaft based on a tension detected by the
tension detection device to control rotation of the at least one of
the supporting shafts to control the tension of the magnetic tape
supported by the one of said plurality of roller members.
5. The magnetic tape manufacturing apparatus according to claim 4,
wherein at least one groove for excluding entrained air of at least
one narrow magnetic tape is formed in an outer peripheral surface
of at least one of the roller members.
6. The magnetic tape manufacturing apparatus according to claim 4,
wherein a tension force is applied to the corresponding one of said
roller members proportional to a difference in rotational speed
between the corresponding one of said roller members.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing magnetic
tape and, more particularly, to a method of manufacturing magnetic
tape such as tape for computer data backup, audiotape and
videotape.
2. Description of the Related Art
In a method of manufacturing various types of magnetic tape such as
tape for computer data backup, audiotape and videotape, a wide
web-like magnetic tape material wound in roll form is drawn out
from the delivery side, and slit into a plurality of narrow
magnetic tapes by use of a slitter while being transported, and the
magnetic tapes are wound on cores on the winding side.
A conventional slitter used in the manufacturing of magnetic tapes
is a device that slits a wide web-like magnetic tape material into
a plurality of magnetic tapes by use of pairs of upper and lower
rotary blades. The rotary blades are generally constituted by a
plurality of rotary blades formed as bed knives in roller form and
a plurality of rotary blades in thin disk form, which perform
slitting by giving a shearing force to the magnetic tape material
between the rotary blades.
In order to obtain a good coil shape in the take-up step in the
manufacturing of the magnetic tape material used in manufacturing
such magnetic tape, the tape material is wound around in the shape
of a crowned roll in which the thickness of the middle portion of
the roll is larger than the thickness of both ends of the roll.
That is, in a magnetic tape material before slitting into a
plurality of magnetic tapes, the outside diameter of the middle
portion of the roll is larger than the outside diameter of both
ends of the roll.
When this magnetic tape material is slit into a plurality of
magnetic tapes, a magnetic tape material taken from the middle
portion of the roll and magnetic tape materials taken from both
ends of the roll have different lengths, thereby causing the slack
of magnetic tapes or the generation of extreme tension in magnetic
tapes. This causes the problem of poor running of magnetic tapes
due to the slack of magnetic tapes, the problem of variations in
the tape width of magnetic tape products due to the tension of
magnetic tapes, etc.
Moreover, cleaning devices each provided with a polishing head are
often provided in the transporting paths of magnetic tapes. Then,
if there are variations in the tension of magnetic tapes, a
polishing head coming into contact with a magnetic tape under low
tension is apt to be especially worn, thus causing a problem as is
often pointed out.
However, the tension control of magnetic tapes by guide rollers
used in conventional apparatuses for manufacturing magnetic tape is
performed by use of a single guide roller (for example, a grooved
suction drum) for a plurality of magnetic tapes. For this reason,
these conventional apparatuses are inadequate for solving the
above-described problems.
On the other hand, as disclosed in Japanese Patent Application
Publication No. 2001-187660, for example, there is a proposal
involving reducing the tension cutoff capacity which causes the
tension of an upstream magnetic tape to differ from the tension of
a downstream magnetic tape. It is said that the occurrence of
problems as described above can be reduced by using devices
incorporating such a proposal.
However, even when various known devices are adopted, it is
difficult to make the tension of individual magnetic tapes
completely uniform, and possibility that problems due to the slack
of magnetic tapes etc. might arise has not been dismissed as
yet.
SUMMARY OF THE INVENTION
The present invention was made in view of this situation and has as
its object the provision of a magnetic tape manufacturing apparatus
which can improve productivity and product quality by controlling
tension to a desired value, in the manufacturing of magnetic tape
which involves slitting a magnetic tape material into a plurality
of narrow magnetic tapes and taking up the narrow magnetic tapes on
cores on the take-up side, so that the tension applied to
individual magnetic tapes becomes constant even in a case where
there are variations in the length of the slit magnetic tapes.
To attain the above-described object, the present invention is
directed to a magnetic tape manufacturing apparatus, comprising: a
tape supply device which draws out a wide web-like magnetic tape
material wound in roll form from a delivery side; a slitter which
slits the magnetic tape material into a plurality of narrow
magnetic tapes; a tape take-up device which takes up the narrow
magnetic tapes individually on cores on a take-up side; and a tape
transporting device which is provided between the slitter and the
tape take-up device and guides the narrow magnetic tapes to the
tape take-up device, wherein: the tape transporting device includes
a plurality of roller members which support the narrow magnetic
tapes, the plurality of roller members are mounted on a plurality
of supporting shafts, respectively, and an eddy current type clutch
is internally mounted on at least one of the plurality of
supporting shafts, the eddy current type clutch controlling
rotation of the one of the plurality of supporting shafts to
control tension of the narrow magnetic tape supported on the roller
member mounted on the one of the plurality of supporting
shafts.
According to the present invention, in the tape transporting device
which is provided between the slitter and the tape take-up device
and guides the narrow magnetic tapes to the tape take-up device,
the plurality of roller members supporting the narrow magnetic
tapes are mounted on the plurality of supporting shafts,
respectively, and an eddy current type clutch is internally mounted
on at least one of the plurality of supporting shafts so that the
eddy current type clutch controls rotation of the one of the
plurality of supporting shafts to control tension of the narrow
magnetic tape supported on the roller member mounted on the one of
the plurality of supporting shafts. Therefore, by making the
tension of the individual magnetic tapes uniform, productivity and
product quality can be stabilized and improved and yield can also
be improved.
Furthermore, according to the present invention, a driving source
(for example, a motor) is unnecessary and hence the space required
for the wiring of the driving source etc. is unnecessary, offering
also the advantage that space savings can be accomplished.
BRIEF DESCRIPTION OF THE DRAWINGS
The nature of this invention, as well as other objects and
advantages thereof, will be explained in the following with
reference to the accompanying drawings, in which like reference
characters designate the same or similar parts throughout the
figures and wherein:
FIG. 1 is a configuration view of a magnetic tape manufacturing
apparatus used in the present invention;
FIG. 2 is a side view of a slitter;
FIGS. 3(a) and 3(b) are configuration views of roller members used
in a magnetic tape manufacturing apparatus of the present
invention;
FIGS. 4(a) and 4(b) are partial configuration views of an eddy
current type clutch; and
FIG. 5 is a configuration view of another embodiment of roller
members.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of a magnetic tape manufacturing apparatus
related to the present invention will be described below with
reference to the attached drawings.
A magnetic tape manufacturing apparatus 10 according to an
embodiment of the present invention, which is shown in FIG. 1 as an
example, comprises a tape supply device 13, which draws out a wide
web-like magnetic tape material 20 wound in roll form from the
delivery side; a slitter 14, which slits the magnetic tape material
20 into a plurality of narrow magnetic tapes 26; a tape take-up
device 50, which takes up the magnetic tapes 26 individually on
hubs (cores) 18 of winding reels 17 on the take-up side; and a tape
transporting device 60, which is provided between the slitter 14
and the tape take-up device 50 and guides the individual magnetic
tapes 26 to the tape take-up device 50 while supporting the
respective magnetic tapes by means of roller members 22, 22 . . . ,
which are guide rollers. FIG. 2 is a schematic illustration of an
example of the slitter 14.
As shown in FIG. 1, in the tape supply device 13, the magnetic tape
material 20 wound in roll form is attached to a hub 12 (a core) of
an unwinding reel 11. Usually, the magnetic tape material 20 is
manufactured by forming a magnetic layer containing ferromagnetic
particles on a nonmagnetic backing layer by the application
process, the vacuum deposition process, etc. and by subjecting the
magnetic layer to orientation treatment, drying treatment, surface
treatment, etc.
The slitter 14 has a plurality of pairs of upper and lower rotary
blades 30 and 32 to slit the wide web-like magnetic tape material
20 into the plurality of narrow magnetic tapes 26, 26, . . . by
giving a shearing force to the magnetic tape material 20 between
the lower rotary blades 30 and the upper rotary blades 32. As shown
in FIG. 2, the plurality of lower rotary blades 30, 30, . . . are
formed as bed knives in roller form, and the plurality of upper
rotary blades 32, 32, . . . are formed as thin disks.
The lower rotary blades 30 are engaged and fixed to a lower shaft
34 with spacers 36, and the upper rotary blades 32 are engaged and
fixed to an upper shaft 38 parallel to the lower shaft 34 with
spacers 40. The lower rotary blades 30 and the upper rotary blades
32 are arranged so that their sharp edges work one against the
other. The upper rotary blades 32 are urged by a spring (not shown)
toward the right side in FIG. 2 along the shaft 38 and positioned
with the cutting edge portions of the upper rotary blades 32
abutting against the cutting edge portions of the lower rotary
blades 30. The upper shaft 38 and the lower shaft 34 are
respectively connected to motors 41 and 43, which can vary
rotational speed freely so that the peripheral speed of the upper
rotary blades 32 and the peripheral speed of the lower rotary
blades 30 can be individually varied.
Between the unwinding reel 11 and the slitter 14 are arranged a
plurality of guide rollers 21, 21, . . . , which constitute a
transporting path of the magnetic tape material 20, and a grooved
suction drum 24, which controls the transporting speed of the
magnetic tape material 20. The grooved suction drum 24 is connected
to a motor (not shown) capable of varying rotational speed freely,
and appropriately varies the transporting speed of the magnetic
tape material 20 by rotating with the magnetic tape material 20
sucked on the peripheral surface of the grooved suction drum
24.
The rotational speed of the hub 18 (the core) of the winding reel
17 in the tape take-up device 50 is controlled on the basis of the
peripheral speed of the grooved suction drum 24. A device which
controls the transporting speed of the magnetic tape material 20 is
not limited to the grooved suction drum 24, and it is also possible
to use other mechanisms such as a pair of a capstan and a pinch
roller which pinch and transport the magnetic tape material 20.
The tape transporting device 60 is provided between the slitter 14
and each of the winding reels 17. Each tape transporting device 60
is provided with a tension roller 28 and a plurality of roller
members 22, 22, . . . . The tension in the transporting direction
of the magnetic tape material 20 during slitting is arbitrarily
adjusted by the tension roller 28. Each tape transporting device 60
is also provided with a cleaning device C etc. if required as shown
in the drawing.
FIGS. 3(a) and 3(b) are configuration views of roller members 22
used in the tape transporting device 60 in the magnetic tape
manufacturing apparatus 10 according to the embodiment of the
present invention. FIG. 3(a) is a perspective view showing how the
plurality of roller members 22, 22, . . . are supported by a
supporting shaft 23, and FIG. 3(b) is a partial sectional view
showing the construction of one of the roller members 22. In FIG.
3(b), the upper half is shown in section.
The roller member 22 is constituted by a boss 62 forming the outer
peripheral portion, a bearing 64 fitted into the inner
circumference of the boss 62, a stopper ring 76 to prevent the
bearing 64 from slipping off, and an eddy current type clutch
80.
The boss 62 is constituted by two members: a boss main body 62A
which is a member disposed on the inner circumference side, and a
crown ring 62B which is a member disposed on the outer peripheral
side of the boss main body 62A. This constitution is advantageous
because the boss main body 62A which requires dimensional accuracy
can be fabricated from a metal material, for example, and because
the crown ring 62B which requires the control of hardness, crown
shape, etc. can be fabricated from a rubber material, a resin
material, etc., for example. However, the boss main body 62A and
the crown ring 62B may be fabricated by a one-piece material.
Grooves 90, 90, 90 to exclude entrained air of the magnetic tape 26
are formed on the outer peripheral surface of the boss 62. Also,
the inner circumferential diameter of the bearings 64, 64 has such
a size that allows the supporting shaft 23 to be fitted into.
In the present invention, it is required that at least one roller
member 22 of the roller members 22, 22 . . . of the tape
transporting device 60 be provided with an eddy current type clutch
80 as shown in the drawings.
FIGS. 4(a) and 4(b) are views showing the construction of an eddy
current type clutch 80. FIG. 4(a) is a partially enlarged view of
FIG. 3(b), and FIG. 4(b) is a partially enlarged view of an example
that is a little different from the eddy current type clutch of
FIG. 4(a). Both drawings show the construction of the roller
members 22 corresponding to one magnetic tape 26.
In FIG. 4(a), a magnet holding ring 66 is fitted onto the
supporting shaft 23 not shown in the drawing (refer to FIG. 3(a)).
Similarly, an inner ring 64A of a bearing 64 is also fitted onto
the supporting shaft 23. Therefore, the magnet holding rings 66 and
the inner rings 64A of the bearings 64 of all roller members 22
rotate integrally with the supporting shaft 23. In order to ensure
that the magnet holding ring 66 also serves as a spacer ring, the
width of the magnet holding ring 66 is formed in such a manner that
the magnet holding ring 66 protrudes from the end surface of the
boss 62 (62A).
A flange 70 is formed at the outer periphery in the vicinity of the
right-hand portion of the magnetic holding ring 66, depressions are
formed at equal intervals on the same circumference of a circle on
the left side of the flange 70, and a magnet 68 is fitted into each
of these depressions. In order to prevent the leakage of magnetic
flux, it is preferred that the flange 70 be made of iron.
On the other hand, on the right side of the inner circumferential
portion of the boss main body 62A, ring-shaped conductor plates 72
having roughly the same size of the flange 70 are arranged at a
prescribed distance from the magnets 68 so as to be opposed
thereto. The conductor plates 72 are fixed to the right side of the
inner circumferential portion of the boss main body 62A through
iron rings 74 to prevent the leakage of magnetic flux. The size and
shape of the iron ring 74 are almost the same as those of the
conductor plate 72. The conductor plate 72 is made of copper or
aluminum etc.
The outer ring 64B of the bearing 64 is fitted onto the inner
circumferential portion of the boss main body 62A and, as described
above, the conductor ring 72 and iron ring 74 are also fixed to the
boss main body 62A. Therefore, the boss main body 62A, conductor
plate 72 and iron ring 74 of each of the roller members 22 rotate
integrally with the outer ring 64B of the bearing 64. Also, these
members can rotate independently of the supporting shaft 23.
As a result of a constitution as described above, the eddy current
type clutch 80 is formed between each of the boss main bodies 62A
etc. and the supporting shaft 23. When the supporting shaft 23 of
the roller member 22 is driven so as to transport the magnetic tape
26, each eddy current type clutch 80 transmits the rotation of the
supporting shaft 23 to each of the boss main bodies 62A. In the
eddy current type clutch 80, an eddy current is generated in the
conductor plate 72 in response to a relative motion between the
magnet 68 which rotates along with the supporting shaft 23 and the
conductor plate 72 which is fixed to the boss main body 62A and
opposed to the magnet 68. Due to the attraction by a primary
magnetic flux by the magnet 68 and a secondary magnetic flux by the
eddy current generated in the conductor plate 72, each of the boss
main bodies 62A is rotationally driven at a given torque in
response to the rotation of the supporting shaft 23.
The torque of the eddy current type clutch 80 is in proportion to a
difference in the rotational speed of the supporting shaft 23 and
the rotational speed of each of the boss main bodies 62A. For this
reason, in a case where the difference in the length of magnetic
tapes 26 is 0.1%, also the rotational speed of the eddy current
type clutch 80 shows a difference of 0.1% and the difference in the
tension which is applied is suppressed to 0.1%. Therefore, the
tension of each of the magnetic tapes 26 becomes uniform.
In this manner, the tension applied to the magnetic tapes 26 can be
controlled by the eddy current type clutch 80 and it is possible to
make the tension of a plurality of magnetic tapes 26 uniform.
Incidentally, the construction of the eddy current type clutch 80
which controls tension is not limited to the above-described
construction, and other constructions can be adopted.
Although FIG. 4(b) shows an eddy current type clutch 80 based on a
similar principle, this eddy current type clutch 80 differs from
that of FIG. 4(a) in some points of construction. In FIG. 4(b), the
flange 70, conductor plate 72 and iron ring 74 are formed in the
shape of a wide and thin-walled ring. However, the functions of all
of these components are almost the same as those shown in FIG.
4(a).
Although the magnet 68 is fixed on the side of the supporting shaft
23 and the conductor plate 72 and iron ring 74 are fixed on the
side of the boss main body 62A in the above two examples, it is
also possible to adopt a construction which is reverse to this. The
radial position of the roller members 22 in which the eddy current
type clutch 80 is arranged is not especially limited.
An eddy current type clutch disclosed in Japanese Patent
Application Publication No. 2000-185850, for example, etc. can also
be adopted.
Incidentally, various publicly known devices such as a slip ring
can be adopted as a device for taking out the eddy current
generated in the conductor plate 72 to the outside.
Next, a method of controlling the tension of the magnetic tape 26
will be described below. The magnetic tape manufacturing apparatus
10 is provided with a tension detection device 52 for each magnetic
tape 26, as shown in FIG. 1. This tension detection device 52 in
which a publicly known constitution is adopted is generally called
a tension pick etc.
From the tension detected by this tension detection device for each
magnetic tape 26, feedback control is performed to the number of
revolutions of the supporting shaft 23 and the tension of each
magnetic tape 26 is made uniform by a desired value. Incidentally,
it is also possible to adopt a constitution in which what is called
open control is performed.
FIG. 5 is a configuration view of a roller member 22 having no eddy
current type clutch 80 which can be used in the transporting device
60 and corresponds to FIG. 3(b). The upper half of this drawing is
shown in section. Incidentally, the same members as in FIGS. 3(a)
and 3(b) or members similar to those in FIGS. 3(a) and 3(b) are
given the same reference numbers and characters and their
descriptions are omitted. The roller member 22 is constituted by a
boss 62 which composes an outer peripheral portion, bearings 64,
64, a spacer ring 82 which performs the action of adjustment of a
gap from an adjacent roller member 22, and a stopper ring 76.
Grooves 90, 90, 90 to exclude entrained air of the magnetic tape 26
are formed on the outer peripheral surface of the boss 62. Also,
the inner circumferential diameter of the bearings 64, 64 has such
a size that allows the supporting shaft 23 to be fitted into.
It is preferred that the outer peripheral surface of at least one
roller member 22 of the roller members 22, 22 . . . of the tape
transporting device 60 be formed to have a crown.
"Crown" is defined in a pulley mechanism in mechanics, and denotes
that the section of a rim surface of a belt pulley is formed in
convex shape in order to automatically prevent a belt from becoming
detached. It is said that the contour of a crown is such that a
circular arc is used, two conical surfaces are combined, a
cylindrical surface is sandwiched with two conical surfaces, and
the like (refer to the Dictionary of Machines, Corona Sha,
1986).
Even when a belt (mainly a flat belt) is unevenly wound onto a belt
pulley to one side, the belt moves to a portion of large diameter
as the belt pulley rotates. Therefore, when the diameter of a
middle portion of a belt pulley in the width direction thereof is
formed to be larger than the diameter of the ends in the width
direction, the belt moves to the middle portion of the belt pulley
in the width direction thereof as the belt pulley rotates and the
motion of the belt becomes stable. The above action also applies a
combination of the roller member 22 of this magnetic tape
manufacturing apparatus 10 and the magnetic tape 26.
The outer peripheral surface of the roller member 22 is preferably
formed from a material having hardness in the range of 30 to 95
specified in JIS K6301A and more preferably formed from a material
having hardness in the range of 60 to 90. This is because the crown
of the outer peripheral surface of the roller member 22 is deformed
and the crown cannot display its effect if the hardness is less
than 30 and flaws are apt to occur in the magnetic tape 26 if the
hardness exceeds 95, both cases being inappropriate.
The radius of curvature of the outer peripheral surface of the
roller member 22 is preferably in the range of 50 to 100 mm and
more preferably in the range of 50 to 85 mm for a magnetic tape
having a width of 4 mm. For a magnetic tape having a width of 30 mm
(1.2 inches), the radius of curvature of the outer peripheral
surface of the roller member 22 is preferably in the range of 500
to 2000 mm and more preferably in the range of 1000 to 2000 mm. In
this manner, optimum ranges suitable for the width of the magnetic
tape 26 have been experimentally ascertained.
As described above, the configuration of the crown in which the
outer peripheral surface of the roller member 22 is a circular arc
in section was described. However, the crown shape is not limited
to the above and it is possible to adopt various sectional shapes,
such as a trapezoidal section, a parabolic section, an elliptic
shape, a hyperbolic section, a section obtained by combining two
conical surfaces, and a section obtained by sandwiching a
cylindrical surface with conical surfaces.
The composition ratio of roller members 22 not provided with such
an eddy current type clutch 80 to the roller members provided with
the eddy current type clutch 80 shown in FIGS. 3(b), 4(a) and 4(b)
can be optimized by the width of the magnetic tape 26, material of
the magnetic tape 26, manufacturing conditions, etc.
Incidentally, as a matter of course, it is also possible to adopt
the construction shown in FIG. 5, in which the outer peripheral
surface of the roller member 22 is formed in crown shape and given
a prescribed hardness, to the roller member 22 provided with the
eddy current type clutch 80 shown in FIGS. 3(b), 4(a) and 4(b).
Also, the position, number, etc. of the roller members 22 provided
in the tape transporting device 60 are not limited to the
constitution shown in the drawings and various modes can be
adopted. Also, even if the outer peripheral surface of the roller
member 22 is not formed in crown, the present invention is
effective.
Next, the operation of the magnetic tape manufacturing apparatus 10
configured as described above will be described below. First, the
magnetic tape material 20 in roll form which is wound on the
unwinding reel 11 of the tape supply device 13 is continuously
drawn out of the unwinding reel 11 and transported to the slitter
14. And by use of the slitter 14 the magnetic tape material 20 is
slit into a plurality of magnetic tapes 26, each of which is
transported by the roller members 22, 22 . . . of the transporting
device 60 and wound on the hub 18 of the winding reel 17 of the
tape take-up device 50. As a result of this, for example, the
magnetic tape material 20 is slit into 100 to 500 portions and
magnetic tapes 26 each having a specified width (for example, 12.65
mm, 25.4 mm or 3.81 mm) are produced.
In this series of steps, at least one roller member 22 of the
roller members 22, 22 . . . of the tape transporting device 60 is
provided with the eddy current type clutch 80 and the tension of
the magnetic tapes 26 during transporting can be controlled, so
that problems ascribable to the slack of magnetic tapes etc. will
not arise even if the length of magnetic tapes shows variations to
some extent.
As described above, according to the present invention, in the tape
transporting device which is provided between the slitter and the
tape take-up device and guides the narrow magnetic tapes to the
tape take-up device, the plurality of roller members supporting the
narrow magnetic tapes are mounted on the plurality of supporting
shafts, respectively, and an eddy current type clutch is internally
mounted on at least one of the plurality of supporting shafts so
that the eddy current type clutch controls rotation of the one of
the plurality of supporting shafts to control tension of the narrow
magnetic tape supported on the roller member mounted on the one of
the plurality of supporting shafts. Hence, by making the tension of
the individual magnetic tapes uniform, productivity and product
quality can be stabilized and improved and yield can also be
improved.
Furthermore, according to the present invention, a driving source
(for example, a motor) is unnecessary and hence the space required
for the wiring of the driving source etc. is unnecessary, offering
also the advantage that space savings can be accomplished.
It should be understood, however, that there is no intention to
limit the invention to the specific forms disclosed, but on the
contrary, the invention is to cover all modifications, alternate
constructions and equivalents falling within the spirit and scope
of the invention as expressed in the appended claims.
* * * * *